Update TrackNamespaceManager

[tetter27]

Changes

• Name changed: TrackNamespaceManager -> PubSubRelationManager
• Refactored the folder structure and the model for pubsub management
• Supported Subscribe ID and Track Alias (Relay side only)
• Changed processes around PubSubRelationManager in message handlers
• Fulfilled almost all processes in new functions with unit tests.

TODO

• Support Subscribe ID and Track Alias in client sides (will handle at next PR)
• Names of PubSubRelationCommands are too long (Issue Names of PubSubRelationCommands are too long #104)
• Redundant in the flow of processing in unit tests (Issue Redundant in the flow of processing in unit tests #105)
• Error handlings in PubSubRelationManager is incomplete (will handle when Termination Error Code supported)

[codecov]

Codecov Report

Attention: Patch coverage is 90.45699% with 71 lines in your changes missing coverage. Please review.

Project coverage is 77.37%. Comparing base (e8b18dc) to head (01e87a8).
Report is 21 commits behind head on impl/subscribe_id_and_track_alias.

Additional details and impacted files

@@                          Coverage Diff                          @@
##           impl/subscribe_id_and_track_alias     #103      +/-   ##
=====================================================================
+ Coverage                              74.18%   77.37%   +3.19%     
=====================================================================
  Files                                     39       45       +6     
  Lines                                   1445     1830     +385     
=====================================================================
+ Hits                                    1072     1416     +344     
- Misses                                   373      414      +41     

Components	Coverage Δ
moqt-core	91.91% <96.52%> (+1.10%)	⬆️
moqt-server	66.15% <87.74%> (+3.54%)	⬆️